This invention relates generally to orthopaedics and, in particular, to apparatus and methods of use enabling multiple bone resections to be performed for different-sized implants using a common fixture.
Prosthetic joint components are being installed with increasing frequency due to the enhanced stability and longevity of improved implants and surgical techniques. As a consequence, younger patients are electing joint-replacement surgery to enhance movement or alleviate pain.
In many joint-replacement situations, it is common practice to use bone-cutting guides to perform resections that correspond to the surfaces of a final implant used for fixation. In the case of primary knee-replacement surgery, for example, a stem is introduced into the distal femoral intramedullary canal to which various measurement and cutting appliances are attached.
Typically, a distal cutting guide is first installed on the stem, which is used to create a flat surface on the very end of the bone. A sizing jig is then attached in contact with this surface. Such jigs typically include adjustable feelers which touch the bone anteriorly and posteriorly, enabling the surgeon to obtain a visual indication of the correct-size implant for the patient""s physiology.
Having determined the appropriate size, pins (or drill holes) are introduced into the end of the bone, and a cutting guide specifically adapted for a particular size of implant is fitted onto the pins, enabling the anterior, posterior and chamfer cuts to be performed. Typically, the location of the pins also takes into account the degree of joint rotation required, which is on the order of three degrees of external rotation for knee-replacement surgery.
Although the system just described functions adequately in most cases, it does present certain drawbacks which tend to consume time and compromise accuracy.
Broadly and in general terms, this invention provides a device incorporating a plurality of cutting guides, wherein at least one of the guides is used to resect or otherwise modify a bone to receive a prosthetic element of a particular size, and one or more additional guides to modify or resect the bone in conjunction with a prosthetic element of a different size. Although the specification and drawings focus on primary total knee arthroplasty, it will be apparent to one of skill in the art of orthopaedic surgery that the inventive principles disclosed here are equally applicable to other joints and bone-modification situations that might benefit from apparatus and methods enabling multiple bone resections to be performed for different-sized implants using a common fixture.
A device for cutting a bone to receive one of a plurality of differently sized prosthetic elements according to the invention comprises a body having a plurality of bone-cutting guides, including a first guide associated with cutting the bone to receive one of the prosthetic elements, and a second guide associated with cutting the bone to receive a different one of the prosthetic elements. In the preferred embodiment the guides take the form of parallel, spaced-apart slots extending through at least a portion of the body, though alternative guides may be provided for different cutting tools such as osteotomes and routers.
In a preferred embodiment, the device further includes a fixture enabling the body to be moved relative to bone to assist the practitioner in determining which of the prosthetic elements and associated guide should be used to resect the bone. The fixture may further include one or more bone-measurement gauges to provide additional assistance in determining which of the prosthetic elements and associated guides should be used. The various guides may also be oriented relative to the body and/or its direction of movement to account for external joint rotation.
Where the bone-cutting guides are configured to resect a distal femur so as to receive a femoral prosthesis in conjunction with knee-replacement surgery, a plurality of guide sets may be provided for anterior, posterior, and associated chamfer cuts for a plurality of differently sized femoral prosthesis. In this case, the body will preferably feature one or more sets of spaced-apart saw-receiving slots, including a first slot to resect the bone to receive a femoral prosthesis of a first size, and a second slot to resect the bone to receive a femoral prosthesis of a second size, different from the first.